Its where you throw on a British/Irish punk accent, dress like a punk rocker (Ramones, Sex Pistols, etc.).
*Note- These bands are just examples, being a punk is about being bold and doing something unique and original. Also, I'm not responsible for any anarchist activity you do on this day, or any other day.

It's always to be celebrated on January 31st (Johnny Rotton's Birthday. It's made as a response to Natinoal Emo Day.